1. Field of the Invention
This invention relates to an agitating mill. Such mill is known from Published German Application No. 17 57 942.
2. Description of the Prior Art
In the known mills of that kind the inlet is disposed in or close to one end of the substantially cylindrical housing or grinding vessel and the outlet is disposed in or near the opposite end. The inlet and outlet consist of tubular ports.
Mills in general are desired to have a high throughput rate and to effect a fine division, i.e., the amount of coarse particles in the outlet should be minimized.
A higher throughput rate involves a supply of more energy to the process. A major part of said energy is converted to heat and the resulting temperature rise imposes a limit on the throughput rate. If the material to be ground is supplied to the mill together with air so that the fines are discharged together with air, that air stream will effect a cooling but such cooling--and also the throughput rate--will be restricted. A disadvantage which has been recognized resides in that the outlet is relatively small so that even an operation at a restricted throughput rate will result in a relatively high velocity of flow in the outlet and, as a result, the flowing air will entrain coarse particles at a relatively high rate.
Whereas the coarse particles can be removed by a succeeding pneumatic separator, this will involve a high expenditure. For this reason, cooled air has already been used as an entraining fluid and other mills have been supplied with lumps of frozen carbon dioxide. Each of said practices involves high costs.